Bread made using only whole wheat flour doesn't rise well, resulting in a heavy, dense bread. Gluten is the stretchy fiber in bread that holds all those tiny pockets of gas the yeast make, and hence allows the rising. Adding gluten or adding white flour achieve the same goal, that goal being a loaf of bread your family will eat. You can make bread using only wheat flour, but it is best if you adjust your tastes to whole wheat gradually. Start with half white, and over time make it more wheat and less white. You can find recipes that use only whole wheat flour; keep looking.